Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.799956
Title: Modelling laser-plasma interactions for the next generation of high-power laser experiments
Author: Savin, Alex
ISNI:       0000 0004 8507 0023
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2019
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Abstract:
Investigating new regimes of laser-plasma interactions requires advances in at least two technologies: targets and laser systems. Exploring these regimes includes developing diagnostics to obtain more information about complex systems such as inertial confinement implosions and constructing models that consider entirely novel and unexplored phenomena. This thesis initially considers implementing state-of-the-art "mid-density" targets made of foam on current petawatt-class laser systems; particularly the application of foams to ion acceleration. It is highlighted that foam targets potentially pave the way for laser systems to realise collisionless shock acceleration as a high energy quasimonoenergetic ion source. A theoretical approach modelling the predicted energy distribution function for shock-accelerated ions is presented with both classical and relativistic formulations. The full, albeit narrow, parameter space for collisionless shock acceleration is mapped and it is shown that there are several pre-existing laser systems that could realise high-energy narrow-band proton beams. Impending multipetawatt laser systems are then considered but it is immediately highlighted that the absorption processes in this new regime may not be fully understood. Therefore, the thesis segues into developing a theory that models absorption in the newly dubbed ``post-ponderomotive'' regime. One absorption mechanism, the Zero Vector Potential process is given a complete description, the predictions of which are validated through numerical simulations. This discussion then considers the limit of the post-ponderomotive regime where quantum electrodynamic effects are predicted to be perturbations. The theory is modified to include the effects of electron-positron pair production and, again, a simulation campaign verifies the theory. Applications of the Zero Vector Potential mechanism to coherent x-ray generation are also explored, and in particular their potential use generating warm dense matter. Finally, given that no scientific hypothesis can be considered valid until it has been tested through experiment, three experimental designs are proposed that could test the theories and hypotheses presented herein.
Supervisor: Norreys, Peter Sponsor: Engineering and Physical Sciences Research Council ; Science and Technology Facilities Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.799956  DOI: Not available
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